Hello all, I am new to this forum and hoping I can get some help. I have a 1995 k2500 suburban 4x4 with the stock 6.5 gm diesel out of a 1998. It has approx. 140k on it. My issue is I cannot keep it from overheating when I am towing my camper. Which fully loaded with gear and all that good stuff is probably about 7500lb give or take. It's mainly bad when I start hitting some hills, and it doesn't take that big of a hill either. Currently modifications are: 4" exhaust, heath diesel tow /haul prom chip, cold air intake, adjustable mechanical wastegate controller,and PMD relocate ,it also has the dual thermostat set up and I am using the original type gm oem stats, Egt gauge,boost gauge and mechanical water temp gauge. I have also installed a brand new oem type radiator and condenser, the 2000+ 251-603 "new and improved water pump" , Hayden 2886 clutch fan, and the duramax fan blade. It still overheats upwards of 225deg. on a warm summer day in Buffalo,NY when pulling my trailer running up hills. I even turn off the A/C which helps a little but not much. Also, the head gaskets have been replaced and the external engine oil cooler is brand new. I am out of ideas and very frustrated at this point. Note: I am a mechanic have been for 30 years so this is now a mission for me to find and correct !!! Looking for any help...Thank You !!!